At least eight dairy cows in Utah have been hit with H5N1 avian flu in the past two weeks, according to the US Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) most recent updates on the virus in livestock. 

In the past 30 days there have been 26 confirmed detections in dairy cows, with Idaho reporting 15 cases in the past 30 days and Texas reporting three cases.

So far this year 72 cattle have had confirmed H5N1 infections. Last year APHIS tracked 171 H5N1 cases in cattle. In 2024, the year the virus was first detected in cows, the United States saw 917 animals infected.

Utah is also reporting a large H5N1 outbreak among commercial egg-laying chickens in Cache County, according to a separate APHIS tracker. More than 1.2 million birds were affected as of July 6. In the past 30 days, APHIS has confirmed outbreaks in six US flocks, but the Utah outbreak was the only commercial flock affected. The rest were backyard blocks or live-bird markets.

A new study by scientists in the United Kingdom shows “distinct and intensifying” sexual transmission of shigellosis.

In the genomic epidemiology study, a team led by researchers at the University of Cambridge analyzed Shigella sonnei isolates collected from 138 laboratories across the country from September 20, 2004, to February 28, 2020. Their aim was to quantify and compare the geospatial spread of S sonnei in different transmission networks. 

While Shigella bacteria spread through contaminated food and water and have traditionally been a cause of diarrhea in people who travel to low- and middle-income countries, where shigellosis is endemic, it’s become increasingly associated with sexual activity among men who have sex with men (MSM) in the United Kingdom and other high-income countries. Sexual networks have also been associated with the spread of drug-resistant Shigella strains.

“Despite this growing and urgent public health threat, the temporal and geographical spread of Shigella remains poorly understood, including the extent to which spread among MSM and non-MSM communities is distinct and the relative impact of antimicrobial selection in those communities,” the study authors wrote in The Lancet Infectious Diseases.

More intense transmission

Of the 3,514 isolates analyzed, 34.1% came from presumptive MSM (pMSM), 36.1% from non-pMSM, and 29.8% came from high-risk travel. The analysis revealed that sexually transmitted S sonnei spread faster and transmitted more intensely than other domestically acquired S sonnei. In addition, isolates from sexually transmitted shigellosis had greater relative fitness than isolates from high-risk travel transmission.

The researchers also found that azithromycin-resistant S sonnei had a fitness advantage among pMSM, a finding they suggest may be linked to use of azithromycin for gonorrhea infections prior to 2018. 

The authors say the findings highlight a gap in public health management for shigellosis, since traditional recommendations for avoiding it, like washing hands and making sure your food is safe, will have little impact on sexual spread. 

“The development of alternative interventions to address this public health threat is urgently needed,” they wrote.